1. Field of the Invention
The present invention relates to a calibrated mechanical winch, and more particularly, but not by way of limitation, to a calibrated mechanical winch and method of manufacture thereof, the winch being adapted for stretching and tightening wire and/or other cables, tethers and the like by utilization of a manually operable device allowing for the user to ascertain the general level of tension applied to the cable or other tether being acted upon during the stretching operation.
2. History of the Related Art
Many devices have been used for tensioning cables, wires and other tethers over the decades. A common manual approach to tightening wire is seen in the area of fencing. Farm land generally spans many miles and requires a variety of fenced sections that may be manually installed with available equipment. For example, barbed wire is common in various states, such as Texas, and many varieties have been used by farmers, ranchers and the like. The manual stretching of barbed wire between two fence posts is a common practice, even today. Fortunately, the manual stretching of such wire is often facilitated by mechanical winches actuatable by the user. One such mechanical winch is conventionally known as a “come along.” This device allows the user to grasp one end of a strand of fencing, such as a barbed wire strand, and apply a manual force thereto relative to a fixed object and/or another strand of wire. While handy to use, the use of come along type devices has certain disadvantages. One distinct disadvantage is the inability to readily ascertain, with much accuracy, the general level of tension being applied to the wire without some form of independent tension measuring device or method. For this reason, it is common to simply hit the tensioned wire with a metal object, such as a screwdriver or similar item, to ascertain the vibrational tone of the wire and audibly determine if appropriate tightness has been applied thereto. This approach, though common, does not provide precise information as to the tension such that it can be accurately repeated along multiple strands of a fenced section. Uniform tension among the multiple strands of a fenced section is, however, very important and therefore a device providing stretching and such information would prove useful.
The tensioning of wire strands is not the only application where cables, tethers and wires must be stretched. When erecting vertical structures, such as radio or television antenna towers, wire stays or the like are often used. Tensioning devices must be incorporated in such applications in order to avoid the potential risk of property damage and personal injury should the tensioning of the cable or the wire strand fall outside of the engineering specification. While the failure of a wire or cable support for a tower is generally much more catastrophic than the failure of a length of fencing wire, there are many considerations that are common between the two. For example, due to the thermal coefficient of expansion, the ambient air temperature has a direct bearing on the appropriate wire tension. Wires constructed of metallic materials inherently have a known thermal coefficient of expansion. The wire will thus expand and contract as the ambient temperature rises or falls. If, for example, wire is installed in the heat of the summer at a select tension, when the ambient temperature drops in the autumn and winter months, the metal in the wire will contract thereby increasing the load on the wire; possibly resulting in the wire breaking. For this reason, it would be important to observe the degree of tension, relative to the ambient temperature, placed upon a wire, cable, tether, or the like during the tensioning process.
Various approaches to measuring tensioning of wire and cable have been addressed over the years. For example, U.S. Pat. No. 3,791,210 to Taylor discloses a tension measuring device that measures cable tension as a function of deflection of its component members. U.S. Pat. No. 4,408,925 to Louie discloses a turnbuckle tensioner which applies tension to a cable through the deflection of a series of belleville washers. U.S. Pat. No. 5,485,762 to Rothman discloses a cable tensioner which uses a linear ratchet to apply tension to a cable. U.S. Pat. No. 6,279,415 to Chance, et al. discloses a cable tensioner that utilizes a linear spring to apply tension to a cable. However, none of these inventions contemplate a come-along style mechanical winch that is calibrated to provide a accurate measurement of cable tension while the wire or cable is being stretched by a user.
It would thus be an advantage to provide a manual winch capable of indicating the degree of tension being applied a wire or cable during a manual tensioning procedure. It would be a further advantage for such a device to be in a configuration that works in a fashion to similar come along devices that are commonly used and well known in the farming and ranching industry. The present invention provides such an improvement by utilizing a mechanical winch having a tension calibration feature incorporated therewith.